US President Joe Biden’s Democrats have inched closer to keeping control of the Senate, with a projected win in Arizona following the midterm elections.
Three days after Americans voted, the BBC’s US partner CBS estimates Democrat Mark Kelly has beaten Republican challenger Blake Masters.
That would leave the Senate at 49 Democratic seats and 49 Republican seats.
Just Nevada and Georgia are yet to be decided.
The vote count in Nevada is neck and neck, while Georgia’s race will be settled by a run-off election next month.
If Democrats win either of the two remaining races they will remain in control of the upper chamber of Congress because the US vice-president can cast a tie-breaking vote on their behalf.
Republicans could still take control of the US House of Representatives as votes continue to be tallied from a handful of districts after Tuesday’s elections.
If the Republicans win either or both chambers of Congress they could thwart much of Mr Biden’s agenda.
Mr Kelly, a former astronaut whose wife, Gabby Giffords, survived an assassination attempt when she was a US lawmaker, was first elected two years ago to serve out the remainder of the late John McCain’s Senate term.
In a statement, Mr Kelly said: “From day one, this campaign has been about the many Arizonans – Democrats, Independents, and Republicans – who believe in working together to tackle the significant challenges we face.
“That’s exactly what I’ve done in my first two years in office and what I will continue to do for as long as I’m there.”
Mr Masters, a 36-year-old venture capitalist, had been endorsed by former President Donald Trump without political experience. He had refused to accept the 2020 election results and repeated false claims of election fraud.
The Masters campaign did not immediately acknowledge the defeat, while various Republicans have alleged that vote-counting was marred by fraud and incompetence.
However, election official Bill Gates, himself a Republican, called for all those involved to “calm down a little bit and turn down the rhetoric”.
The result is another blow to the Republicans, who were hoping for a “red wave” – an electoral rout which would deliver a harsh rebuke of President Joe Biden and the Democrats.
While the party has made modest gains and remains favoured to win the House of Representatives, the Senate remained hotly contested and the Democrats have performed better than expected.
Mr Biden has said the election was a “good day” for US democracy.
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The midterm elections are for Congress, which is made up of two parts – the House of Representatives and the Senate.
Congress makes nationwide laws. The House decides which laws are voted on while the Senate can block or approve them, confirm appointments made by the president and, more rarely, conduct any investigations against him.
These votes are held every two years and when they fall in the middle of the president’s four-year term of office.
Each state has two senators, who sit for six-year terms. Representatives serve for two years, and represent smaller districts.
All the seats in the House of Representatives were up for election in the midterms, alongside one-third of the Senate.
Several major states also have elections for their governor and local officials.